Zap <-> SIP choppy voice problem


#1

I’m looking for some help resolving a problem with Zap terminated calls and a sometimes very choppy voice quality in the Zap -> SIP direction (the ZAP end sounds choppy to the SIP user, but SIP sounds OK to Zap end)

asterisk 1.2.7
zaptel 1.2.6
TDM2400 w/ 8 chans (2 modules)
Polycom 301 & 501 phones
Dell 2850

Reading similar issues in this forum and on the asterisk forum, I enabled VAD (silence supression) on the Polycoms, which helped some.

I ran zttest for a few hundred itterations, and got 99.96 for the worst case 99.99 for avg.

I tried disabling the echocancel, and adjusting the echo training.

Ideas anyone?

Thanks - Mark
======== zapata.conf ==============

[channels]

language=en
context=from-pstn
signalling=fxs_ks
rxwink=300 ; Atlas seems to use long (250ms) winks
usecallerid=yes
hidecallerid=no
callwaiting=yes
usecallingpres=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer=yes
cancallforward=yes
callreturn=yes
echocancel=yes
echocancelwhenbridged=no
echotraining=200
rxgain=8.0
txgain=5.0
group=0
callgroup=1
pickupgroup=1
immediate=no
relaxdtmf=yes